There are many synonymous phrases that can be used in place of the phrase "cheery vein," which typically refers to a person's upbeat, positive attitude or demeanor. Some alternative phrases could include "sunny disposition," "merry temperament," or "jovial spirit." Other options might include "bright outlook," "optimistic perspective," or "happiness vibe." No matter the specific wording, the underlying meaning remains the same: these phrases all describe someone who is consistently joyful and optimistic, even in the face of adversity. Whether you use "cheery vein" or one of its many synonyms, the sentiment is sure to bring a smile to anyone's face.